Many of my patients ask me when is the best time to operate after an ACL injury. Because many patients want to put off surgery after an injury because of work, school, and many other factors, they want to wait until they are free to come back later. I would say: the sooner the better, especially for younger patients. Why? Let me give you 3 more typical examples. The first one is a student who just finished her midterm exams. 1 year ago, she fell and damaged her ACL, an old specialist suggested her conservative treatment, and after a month in a cast, she started to recover gradually, but she never fully recovered, not only could she not exercise strenuously, but she often had weak legs when going up and down the stairs. 1 month ago, when she went down the stairs, her legs got weak and she fell down again, her knee swelled and hurt so much that she could not walk. A very pretty little girl had to use crutches. After a midterm examination, she came to me and found an old ACL III° injury, combined with a medial collateral ligament III° injury and a medial meniscus injury. I told her father that if the first injury had been treated with minimally invasive surgery to reconstruct the ACL, the second injury would have been avoided, but this time not only the ACL, but also the medial collateral ligament and meniscus had to be repaired, making the surgery more difficult and the post-operative recovery less effective than if the ACL alone had been done, because scarring and joint stiffness are likely to occur after medial collateral ligament surgery, and The young girl will have an additional surgical incision scar on her leg. The second one was an amateur player who had an ACL injury for more than 1 year and was still playing soccer, he sprained it again once playing soccer and came to me with very severe pain, we did arthroscopy and found that most of the ACL was gone, there was also intercondylar fossa hyperplasia and a compound tear from the posterior horn of the medial meniscus to the body, there was no way to preserve it, we did an arthroscopic posterior horn of the medial meniscus resection + ACL double-bundle reconstruction. I told the patient that even if he recovers later, there is still a high chance of developing osteoarthritis in the knee later if he plays football again because half of the medial meniscus has been removed. However, if the surgery was done early in the injury, he had a good chance of returning to the field. The patient regretted not having the surgery earlier and having to say goodbye to the green field early. The third was a military man who had a bad knee injury for many years. He had already had a medial meniscus removal when he came to me, but perhaps because the surgeon did not have the surgical skills to perform ACL reconstruction, he did not have his ACL reconstructed, and we did an autologous tendon ACL reconstruction, but the patient never recovered very well, even though the reconstructed ligament was stable after performing anterior drawer, axial shift, and The patient kept feeling pain in the medial joint space, and MRI review revealed cartilage degeneration on the medial tibiofemoral joint surface. An arthroscopic exploration and cleanup revealed type 4 damage and degeneration of the cartilage of the medial femoral condyle, and we did a microfracture, but the patient was no longer likely to make a full recovery and had to transfer out of his beloved unit as a result. If these examples don’t prove it, the evidence from evidence-based medicine is even more telling, such as Millett PJ et al who found a 4-fold increase in the odds of medial meniscus injury in patients who had an injury for more than 6 weeks before surgery compared to those who had surgery within 6 weeks of injury. Given the above examples, I would recommend that younger patients undergo minimally invasive surgical treatment sooner (preferably within 6 weeks) after an ACL injury to ensure maximum recovery. Those patients who delay surgery have a much higher chance of developing sequelae. Once again, it is important to find the right doctor for your knee injury, and to see a physician specializing in sports medicine or joint surgery.